Why windows steam up on the inside, and what to do
Every autumn we hear the same question: we have new windows and they are steaming up, so are they faulty? Almost never. Usually it is the opposite: the windows are doing their job.
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Where the water comes from
Air always contains water vapour, and the warmer it is, the more it can hold. When warm, moist air touches a cold surface it cools, can no longer hold all that vapour, and the excess settles as droplets. Exactly the same happens to a bottle taken out of the fridge.
In winter the coldest surface in a room is the glass. That is why condensation appears there and not on the walls.
Why it started after the windows were replaced
Old wooden windows let air through the gaps, and moisture went with it. The home ventilated itself around the clock without anyone noticing, taking heat with it too. A new window closes airtight, so the moisture that used to escape in the draught now stays in the room.
A family of four gives off several litres of water a day through breathing, showers, cooking, washing, drying clothes and houseplants. That water has to go somewhere.
What helps
- Airing in short bursts: open the window wide for 5–10 minutes two or three times a day. It works better than leaving a sash slightly open all day, and you lose less heat.
- The micro-ventilation position on the handle, if your hardware has one.
- The cooker hood while cooking and the bathroom fan after a shower, and not switching them off straight away.
- Not drying laundry in a room with the window closed.
- Not letting the window sill cover the radiator completely: warm air needs to rise along the glass. If the sill is deep, ventilation slots in it help.
- Not drawing heavy curtains tight against the glass all night.
When it really is a fault
There is one case where airing is not the answer: moisture inside the glass unit, between the panes. You cannot wipe it off, and over time it leaves a cloudy film. It means the unit itself has lost its seal, and it needs replacing.
It is also worth calling if condensation runs in a band along the bottom of the frame, if you can feel a draught from under the glazing bead, or if the sash no longer closes tightly. Often it is just a matter of adjusting the closing pressure, a ten-minute job.
We also repair windows we did not fit: replacing glass units and seals, adjusting and repairing mechanisms. +372 5555 1682.